Added January 2010: It is now possible to ship both Small and Large Flat Rate Boxes with PayPal, as long as you do so through eBay rather than PayPal directly. For my guide on doing that, check out Print Shipping Labels Directly With EBay.

Most sellers choose to ship via the United States Postal Service because of their relatively reasonable rates and easy access to free shipping supplies. One of USPS’s best products is underutilized by many sellers who aren’t familiar with how USPS rates work. Introduced in November 2004, the original USPS Priority Mail Flat Rate Boxes measure 13.25″ by 11.75″ by 3.25″ or 11″ by 8.5″ by 5.5.” The benefit of the Flat Rate Box is that the cost is the same to ship any weight up to 70lbs. The cost is also the same to all destinations within the United States no matter how many zones the package travels. They originally cost $7.10, but the price has increased dramatically to $10.70 in 2010. Nonetheless, it is still cheaper to ship an item that weighs three pounds or more in a Priority Mail Flat Rate Box than in a package with a variable rate (such as a regular envelope or box) for most destinations. USPS variable rates are based on both weight and the package’s destination. As you might have guessed, the farther away the package is going, the more expensive it will be. One other thing, USPS rates only change for every full pound i.e. the cost is the same for every weight between 1lb 1oz and 2lbs or every weight between 3lbs 1oz and 4 lbs so you can round up to the nearest even pound when entering shipping weights. To put it another way, there is a significant price change between a 2 pound package and a package weighing 2 pounds 1 ounce but there is no price change between an item weighing 2 pounds 2 ounces and one that weights 2 pounds 15 ounces. Let’s look at an example of how the Priority Mail Flat Rate Box can save you money.

For the sake of argument, let’s assume you’re shipping a three pound statue from Seattle, Washington zip code 98105 to Detroit, Michigan zip code 48201. The cost for Priority Mail variable rate packaging would be $12.70. With a Priority Mail Flat Rate Box, the cost would be $10.70, a savings of $2.00. For a two pound package the variable rate to Detroit would be $9.55 and the flat rate box would be the same $10.70. For two pounds, variable rate is always cheaper.

Now, let’s say you’re shipping that same three pound statue from Seattle to Los Angeles, California zip code 90001. The cost in Priority Mail variable rate packaging would be $9.00. Of course, the Flat Rate Box still costs $10.70. Here, you actually save $1.70 by shipping the same statue in your own envelope or box rather than using the Flat Rate Box. If the statue was four pounds then the cost in variable rate packaging would be $11.90, so the Flat Rate Box becomes cheaper at four pounds for this destination.

As you can see the cost changes significantly depending on where you are shipping. Familiarize yourself with how much it costs to ship to different areas so you will know when it’s cheaper to use a Flat Rate Box and when it’s cheaper to use variable rate packaging without having to check both for every address. As a rule, variable rate packaging is always cheaper than a Flat Rate Box for a package weighing 2 pounds or less. For two pounds one ounce or more, the Flat Rate Box is often the cheaper choice, unless the package is traveling a relatively short distance.

So far I have discussed the two Flat Rate Boxes that USPS originally introduced in 2004. Since then, USPS has introduced two other sizes. First introduced in March 2008, the “Priority Mail Large Flat Rate Box” measures 12” x 12” x 5-1/2” and costs $14.50 to ship domestically and $12.50 to ship to APO/FPO addresses. APO/FPO addresses are military addresses. To show support for the armed forces, USPS offers a discount on the Large Flat Rate Box when shipping to these addresses which makes the Large Box the ideal solution when shipping to APO/FPO addresses. Personally, I do not have a lot of use for Large Flat Rate Boxes because they are only slightly larger than the regular Flat Rate Box, but if you have an item that does not fit in to the regular Flat Rate Box be sure to check out the Large Box.

Finally, USPS introduced the Priority Mail Small Flat Rate Box in January 2009. It measures 8-5/8 x 5-3/8 x 1-5/8 inches — about the same size and shape as three stacked DVD cases. The cost is $4.95. If you have an item that small that weighs more than 1 pound then it may be wise to ship in this Small Flat Rate Box. There is also a Flat Rate Envelope that also costs $4.90 that may also be useful for smaller items that weigh more than 1 pound.

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The USPS medium flat rate box is the old small flat rate box, but is now twice the price! The medium box used to be called “small” & was $4.95, and now it’s over $10. This new small flat rate box is now the $4.90 box, but it’s waaaaaay smaller in size. USPS has totally jacked up the prices, but they’re playing it off like they just introduced a new box – yeah, for the same price as the former “small” box, only it’s half the size! Prices have DOUBLED, basically.

That isn’t really true. The original flat rate box was $7.10 at its time of release and is now referred to as the medium flat rate box. The original flat rate box was the only size available for about four years. The price has increased each year and currently costs $10.70. The small flat rate box is only about a year old.

I could show you a photo of the original small flat rate box, and the current small flat rate box, if you have an email to which I could send. It would demonstrate that yes, the USPS is – as usual – pinching pennies by “sneaking” changes in (there is absolutely no press release announcing any change in sizes, after doing a Google search, so yes, this is sneaky). I’m sorry to bash your friends at the USPS, but unfortunately, “ugh” is also correct. The USPS has shuffled around their definitions as “ugh” described, in ADDITION to shrinking the smallest flat rate box to 2 inches smaller on each edge (once again, I have photos). Further still, if you try to mail a flat-rate box and have underestimated the weight, you will be charged for the extra weight – on a FLAT RATE box. Explain that one away, please. Yes, I have emailed the USPS asking for some explanations that would make all of this make sense. I was ignored. It’s a difficult endeavor to call into question the anecdotal experience of another. Well, it’s impossible, because the experience EXISTS. You can’t attempt to invalidate something that actually happened, even if you don’t want it to be true. I don’t want my experiences with USPS to be true either – unfortunately, they are. To argue over something that is prove-able and experienced first-hand by me (and not you, apparently) is just silly.
Alas, as UPS interprets the “fragile” sticker to read, “kick me here,” I am forced to use USPS. So, everyone can stop the alarms: Yes, I will bend over and take it. You don’t have to defend yourself so hard.